1. Field of the Invention
The present invention relates to a method of manufacturing a rust-preventing cover and to a rust-preventing cover manufactured by the method.
2. Description of the Related Art
From the time that assembly of a vehicle has been completed to the time that the vehicle is delivered to a dealer or to the purchaser, there are cases in which the automobile is exposed outdoors for a long period of time while being stored or the like. When the vehicle is left in this state, rust may form on the disc rotor, which is an important element of the disc brake device, or the like. Therefore, conventionally, a rust-preventing cover has been used. The following four characteristics are required of a rust-preventing cover: the rust-preventing cover must ensure the rust-proof state of the disc rotor (first requisite characteristic (basic requisite characteristic)); the rust-preventing cover must not deform (open) from the time the cover is shipped from a factory as a product to the time that it is delivered to an assembly factory to be mounted to a vehicle, nor at the time when the rust-preventing cover is mounted to the vehicle on an assembly line at the assembly factory (second requisite characteristic); the rust-preventing cover must not come off easily after being mounted to the vehicle (third requisite characteristic); and the rust-preventing cover must be able to be removed easily when it is not needed (fourth requisite characteristic).
Japanese Utility Model Application Laid-Open JP-U-57-80734 discloses such a rust-preventing cover. The structure disclosed in this publication will be briefly described hereinafter.
As illustrated in FIG. 13, a rust-preventing cover 150 is formed in a substantially annular configuration, and includes a hat portion 152 forming the general surface, a bridge portion 154 which is narrow and formed by cutting away a portion of the hat portion 152, and a pair of flat abutment portions 156 which connect the hat portion 152 and the bridge portion 154. A pair of engagement projections 158 for mounting are formed at predetermined positions in the peripheral direction of the hat portion 152. A leg portion 160, which is used as a handle when the rust-preventing cover 150 is to be removed, is formed integrally with the hat portion 152 at the side thereof opposite the bridge portion 154.
A detent portion 162, which projects outwardly in the radial direction, is formed integrally with the central portion of the bridge portion 154. A first slit 164 is formed at the axis side of the detent portion 162. A second slit 166 is formed between the detent portion 162 and one of the abutment portions 156.
The rust-preventing cover 150 is interposed between an unillustrated disc portion of a disc wheel supporting the tire and an unillustrated disc rotor which is an important element of the disc brake device. In this way, the rust-preventing cover 150 has the first requisite characteristic, which is ensuring that the disc rotor remains rust-proof.
By disposing the detent portion 162 between a pair of claw portions of a caliper, the rust-preventing cover 150 is prevented from turning with respect to the caliper. Further, in this state, end portions of torque members of the caliper abut the pair of abutment portions 156, and the engagement projections 158 engage with the outer peripheral portion of an unillustrated dust cover disposed at the inner side of the disc rotor. The rust-preventing cover 150 is thereby in an elastically mounted state. In this way, the rust-preventing cover 150 has the third requisite characteristic that the rust-preventing cover 150 is not easily removed after mounting to the vehicle.
The following drawbacks are noted when considering the degree to which the rust-preventing cover 150 achieves the second and fourth requisite characteristics.
The rust-preventing cover 150 is often manufactured by a so-called DFM (dry fiber mold) process in which wood chips are made into fibers which are used to prepare a board which is molded into a flat plate shape and used as a base, and thereafter, the board is die cut and then press molded. In this case, because the rust-preventing cover 150 is formed from a material including wood fibers which have a relatively high bonding strength, the rust-preventing cover 150 does not deform (does not open) from the time the cover is shipped from a factory as a product to the time that it is delivered to an assembly factory. In this way, the rust-preventing cover 150 has one part of the second requisite characteristic. However, because the bonding strength is relatively high and the first slit 164 and the second slit 166 are provided, a drawback arises in that the rust-preventing cover 150 deforms easily when mounted to a vehicle in an assembly line at an assembly factory.
Further, in accordance with the above-described structure, by pulling in the direction of arrow A the leg portion 160 which is a handle, the rust-preventing cover 150 breaks from the second slit 166 and is removed. Here, the first slit 164 is formed in order to prevent the detent portion 162 from abutting against the claw portions of the caliper and the breaking force from being absorbed when the tensile force in the directions of arrows B acts on the bridge portion 154 due to the tensile force in the direction of arrow A. More specifically, due to the first slit 164, the detent portion 162 elastically deforms such that the direction of curvature is reversed, and thus, the breaking load concentrates at the second slit 166 and breaks this portion. However, because the bonding strength is high, the breakage strength of the second slit 166 is also high. The fourth characteristic which is the rust-preventing cover 150 being able to be easily removed when not needed is not achieved sufficiently.